Tannic Acid is a basic ingredient in the chemical staining of wood.
The tannic acid or tannin is already present in woods like oak, walnut, and mahogany.

Tannic acid can be applied to woods low in tannin so chemical stains that require tannin content will react.

TANNIN - Other Uses:
Tannic acid is the most common mordant for cellulose fibers such as cotton. Tannin is often combined with alum and/or iron. The tannin mordant should be done first as metal mordants combine well with the fiber-tannin complex.

Directions:
To make a solution to treat woods
lacking tannin content:

1. -- Mix five (5) parts, tannic acid powder into 95 parts of warm water; or (3 Teaspoons intro 8 ounces of warm water).
May also be disolved in denatured alcohol or acetone.